The effect of PMSG on output of estrus synchronisation following using norgestomet in river buffalo

In this experiment, the effect of PMSG on the output of estrus synchronization following using norgestomet implant was investigated in river buffaloes. Twenty two cyclic female river buffalos at unknown stages of estrus cycle were selected and received norgestomet implant (Crestar, 3mg norgestomet, Intervet, Holland), with an injection of GnRH at first day of experiment. On day 7 after norgestomet insertion, females were randomly assigned into two groups considering their age and weight and both groups of control and experiment received PG F2α (15mg prostiol, prozolin, intervet, Holland). The animals in treatment group received PMSG (Folligon, 1000IU, IM, intervet, Holland) in addition to PG F2α. The implant was removed on day 9 after insertion in all females. Estrous detection was conducted using teaser bull, from 12 hours after norgestomet removal for 7 days every 4 hours for at least 30minutes. From the beginning of sfrous until ovulation, ultrasonography was conducted at the time of estrus, 24, 32 and 40 hours after standing estrus. PMSG had no effect on the frequency of estrous response (Treatment: 100%; control: 81.8%), tightness of estrus synchrony within 12 hours (Treatment: 77/8%; Control: 72/8%) and the frequency of ovulation (Treatment: 100%; control: 88.9%; P>0.05). The interval between the end of treatment and the start of estrus in control group (52.5±4.11 hours) was longer than PMSG group (41.8±8.57 hours; P<0.05). In conclusion, PMSG injection, 2 days prior to the termination of 9 days estrus synchronizationprogram could hasten the time of estrous expression in river buffalo. This has to be considered in fixed timed artificial insemination in this species.